1. Field of the Invention
This invention relates to a manual feed apparatus to be mounted on an image printing apparatus such as a copying machine, a laser beam printer, a facsimile apparatus, and the like, and particularly to a manual feed apparatus that maintains stable feed performance even when a large amount of sheets are stacked on it.
2. Description of the Prior Art
As a manual feed apparatus employed as one sheet feed apparatus in an image printing apparatus such as a copying machine, a laser beam printer, and the like, one is conventionally known in which a plurality of sheets mainly comprised of print sheets are stacked on a sheet feed table and are sequentially fed starting from the uppermost sheet. In Japanese Unexamined Patent Publication No. 2001-146343, the inventors of the present applicant disclose an example of a method with which a manual sheet feed table serving as a print sheet stacking member in a manual feed apparatus can be opened/closed with respect to an image printing apparatus such as a laser beam printer by pivot operation, so the manual sheet feed table can be used as a feed apparatus.
The manual feed apparatus disclosed in the above Japanese Unexamined Patent Publication No. 2001-146343 and the like is comprised of a push-up plate for urging a sheet against a feedout roller when the print sheet is fed from the manual feed apparatus, and a manual sheet feed table (opening/closing tray) which is opened/closed and stored. One end of the opening/closing tray is fixed to the image forming apparatus main body. Hence, when the opening/closing tray is in use (in feeding operation), it cannot be vertically moved in an open state. When the manual sheet feed table is to be stored, it is stored after its print sheet stacking surface is closed. When the manual sheet feed table is to perform feed operation, its print sheet stacking surface is opened. At the same time, the push-up plate located in front of (downstream of) the opening/closing tray in the feed direction is pivotally driven and inclined, so it is vertically moved. Thus, the sheet is urged against the feedout roller. With this arrangement, when a large amount of print sheets are stacked, the amount of displacement of the push-up plate which is displaced by pivotal driving increases. Then, the angle at which the sheet abuts against the feedout roller changes largely in accordance with the remaining stacked amount of the sheets. As the angle of inclination becomes large, the inclination of the print sheet in the vicinity of the feedout roller increases to adversely affect the feed performance. In this manner, in the feed apparatus in which feeding conditions change continuously largely, it is very difficult to maintain high feed performance. To decrease the amount of displacement of the push-up plate in the vertical direction and to reduce the angle of inclination, the push-up plate may be formed large, and its pivotal fulcrum may be set far from the feedout roller. Then, however, the feedout roller is positioned deep inside the main body. Consequently, when jamming occurs, it is difficult to recover. Also, the size of the image forming apparatus becomes large.
The present invention has been made in order to solve the above drawbacks of the prior art, and has as its object to provide a manual feed apparatus with which even when the number of sheets that can be stacked on the manual feed apparatus is increased, stable sheet feed performance can be maintained without increasing the size of the image forming apparatus or without degrading the recovery properties against jamming.
In order to achieve the above object, according to the main aspect of the present invention, there is provided a manual feed apparatus having an opening/closing tray which can be stored in an image forming apparatus main body by swing operation, and a feedout member which feeds a sheet stacked on the opening/closing tray, wherein the opening/closing tray is swingably connected to a vertically movable support member which is restricted to be movable in a vertical direction, and the apparatus comprises a vertically movable unit for moving the vertically movable support member in the vertical direction.
According to the second aspect of the present invention, there is provided a manual feed apparatus wherein the sheet is abutted against the feedout member by vertical movement of the vertically movable unit according to the main aspect
According to the third aspect of the present invention, there is provided a manual feed apparatus wherein the vertically movable unit according to the second aspect comprises a rack gear provided to the opening/closing tray or the vertically movable support member, and a pinion gear engageable with the rack gear.
According to the fourth aspect of the present invention, there is provided a manual feed apparatus wherein both the rack gear and the pinion gear according to the third aspect form helical gears, the apparatus has a reference surface on a stationary portion which is not moved by the vertical movement, and an abutting portion on the vertically movable support member, and the abutting portion is abutted against the reference surface by a force in a thrust direction which is generated by driving operation of the pinion gear, thereby positioning the opening/closing tray in a direction perpendicular to a feed direction.
According to the fifth aspect of the present invention, there is provided a manual feed apparatus wherein the vertically movable unit according to the main aspect comprises a string material attached to the vertically movable support member, and a take-up member, attached to a stationary portion which is not moved by the vertical movement, to take up the string member.
As is apparent from the aspects described above, according to the present invention, the manual feed table which is opened/closed and stored is vertically moved in the vertical direction, thereby always setting constant the angle of the sheet with respect to the feedout roller. Therefore, a manual feed apparatus can be provided with which no matter how the number of sheets that can be stacked is increased, stable sheet feed performance can be maintained without increasing the size of the image forming apparatus or without degrading the processing performance against jamming.
In particular, according to the fourth aspect, the abutting member is provided to be fixed to the apparatus main body. Part of the vertical driving force is converted into the thrust direction by using a rack-and-gear mechanism having helical gears, so the vertically movable support member is abutted against the reference surface of the abutting surface. Therefore, in vertical movement, variations in sheet position in the direction perpendicular to the sheet feed direction, which is caused by the backlash of the vertically movable mechanism portion such as the vertically movable support members, guide rails, and the like, can be prevented.
The above and many other objects, features and advantages of the present invention will become manifest to those skilled in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments incorporating the principle of the present invention are shown by way of illustrative examples.